US 6895255 B1
A dual mode mobile unit is arranged to communicate in either a first or second data communications standard, such as combined Bluetooth and 802.11 operation. An interface unit converts received Bluetooth or 802.11 format signals into 802.11 frame format data signals to be provided to a digital signal processor which is programmed to process signals in either standard. The dual mode mobile unit can operate in the 802.11 standard to reserve a time interval for Bluetooth activity during which other 802.11 units will avoid-transmissions to avoid interference.
1. A method for operating a dual-mode mobile unit arranged to transmit and receive signals using first and second wireless protocols, comprising:
operating said mobile unit under said first wireless protocol;
reserving a transmission time interval in a frame of said first wireless protocol; and
operating said mobile unit under said second wireless protocol during said reserved time interval,
wherein said reserving a transmission time is repeated at a selected duty cycle.
2. A method for operating a dual mode mobile unit as specified in
One of the current techniques for providing a wireless local area network which has achieved widespread use, is international standard IFO/IEC standard 8802-11, which is also ANSI/IEEE Standard 802.11 (herein Standard 802.11). This standard provides a uniform specification for a wireless local area network media access control (MAC) and physical layer (PHY) so that equipment from multiple sources works together.
The 802.11 standard is useful for wireless local area networks which may be used in a facility, such as a store, a factory, a research laboratory or a university for providing wireless communication between a stationary system, such as a wired network or a computer and mobile units. The wired network includes one or more access points which interfaced the wired network or computer to the mobile units using radio signals. The mobile units, which may include portable computers having a wireless radio add-on, personal digital assistants, bar code scanners, point of sale devices and the like, communicate with the access point to provide wireless access to the underlying system.
There is currently being developed a specification for the “Bluetooth System” for providing wireless communication over a shorter range, for example providing communication between a portable personal computer and a printer or other devices. The Bluetooth specification is intended to provide less expensive radio protocol technology for communicating over shorter ranges. The draft Bluetooth specification is available at www.Bluetooth.com.
Both the 802.11 system and the Bluetooth system operate in the same 2.4 GHz ISM radio frequency band. The devices in both systems are mobile, and may radiate spread spectrum signals over the frequency range. Accordingly, there is a possibility of the signals from one system interfering with transmissions in the other system and causing loss of data. Also, for many applications it is desirable for a mobile unit to be able to use both systems.
It is an object of the present invention to provide a dual mode mobile unit capable of operating in both the 802.11 system and in a Bluetooth system for communications between the dual mode mobile unit and other units using either system.
It is a further object of the invention to provide methods whereby 802.11 systems and Bluetooth systems can co-exist without signal interference.
In one aspect of the invention there is provided a method for operating a dual mode mobile unit arrange to transmit and receive signals operating using first and second wireless protocols, such as IEEE 802.11 protocol and the Bluetooth protocol. The mobile unit is operated under the first wireless protocol. The mobile unit uses the first wireless protocol to reserve a transmission time interval in a frame of the first wireless protocol for purposes of operating under the second wireless protocol. During the reserved time interval the mobile unit operates under the second wireless protocol to send and receive signals.
In a preferred arrangement, where the first wireless protocol includes requirements for a transmission using that protocol for holding a reserved time, the mobile unit may transmit short transmissions of under the first wireless protocol at the beginning and the end of the reserved time interval.
In one arrangement the dual mode mobile unit operates as a master unit in the second wireless protocol to control the operation of at least slave unit that operates in the second wireless protocol. The dual mode unit can reserve a transmission time interval in a frame of the first wireless protocol and control the slave unit using the second wireless protocol to transmit during the reserved time interval.
Preferably the process of reserving transmission time in the first wireless protocol is repeated at a selected data cycle, which may be altered according to the level of radio activity using the second wireless protocol.
In accordance with the invention there is provided a method for operating a dual mode mobile unit including providing a first transmitter and a first receiver for operating using a first wireless protocol for sending and receiving signals. The first transmitter responds to first protocol baseband signals and the first receiver provides output first protocol baseband signals. A second transmitter is provided for operation using a second wireless protocol and responsive to second protocol baseband signals, and a second receiver is provided for operating using the second wireless protocol providing output second protocol baseband signals. A digital processor is programmed to process signals for both the first and the second protocols. The processor is responsive to receive digital signals in a first protocol frame and provides output digital transmission signals in the first protocol frame format. The output first and second protocol baseband signals from the receivers are converted to received digital signals in the first protocol frame format for the digital processor. The output digital transmission signals in the first protocol frame format are converted to first or second protocol baseband signals for the respective first or second transmitter.
In accordance with the invention there is provided a dual mode mobile unit for operating according to first and second wireless protocols. The dual mode mobile unit includes first and second RF modules respectively for transmitting and receiving signals according to first and second wireless protocols and each responsive to baseband signals for transmission and providing output baseband signals on reception. There is provided a digital processor responsive to received digital signals and digital data signals to be transmitted for processing the digital signals according to one of the first and second protocols. An interface unit is provided for converting received baseband signals from the first and second RF modules and supplying corresponding digital signals to the processor and for receiving digital signals from the processor and supplying first and second corresponding baseband signals to be transmitted by the first and second RF modules respectively.
In a preferred arrangement the processor controls the interface unit to send and receive signals to and from the first and second RF modules. In a preferred arrangement the interface unit receives output baseband signals from the second RF module and supplies corresponding digital signals to the digital processor in a first protocol frame format and receives digital signals from the digital processor in the first protocol frame format and supplies corresponding baseband signals to the second RF module according to the second wireless protocol.
For a better understanding of the present invention, together with other and further objects, reference is made to the following description, taken in conjunction with the accompanying drawings, and its scope will be pointed out in the appended claims.
The present invention addresses the problem of interference that might occur between the communications of mobile unit 10 with access point 102 using the 802.11 standard and communications being carried on by Bluetooth unit 108 using the Bluetooth standard. According to a preferred embodiment of the invention, mobile unit 10 is arranged to communicate using both standards and to coordinate communications using the Bluetooth standard with the communications using the 802.11 standard.
A block diagram of mobile unit 10 is shown in FIG. 1. The communications portion of mobile unit 10 includes an RF module 12 for providing radio communications using the 802.11 standard and a second RF module 14 for providing radio communication using the Bluetooth standard. There is additionally provided an communications processing module 16 and a digital processor module 18. RF module 12 includes a transmitter 22 and a receiver 24, both connected to antenna 26. The transmitter 22 responds to baseband signals provided from module 16 via the WLAN radio interface 34. Transmission baseband signals and received baseband signals are demodulated and modulated by 802.11 baseband modem 38, which, as an example, may be an Alantro modem. Interface 34 and modem 38 are conventional 802.11 modules.
Communications processing module 16 is also connected to RF module 14 which includes Bluetooth transmitter 28 and Bluetooth receiver 30 which are connected to antenna 32. It should be recognized that a single antenna may be provided for both RF modules, and may be switched between the modules according to the current operation.
Communications processing module 16 includes a Bluetooth radio interface 36 and Bluetooth baseband modem 40, again following the standards of the Bluetooth systems.
Modems 38 and 40 are connected to configurable bit-stream processor 42 which receives the 802.11 and Bluetooth baseband signals, strips the overhead data, computes the CRC and provides the message data to first in and first out (FIFO) memory 44 as digital data signals. Received baseband signals from modem 40 are also processed to provide them in the frame format of 802.11 data which is likewise provided to FIFO memory 44.
Configurable bit-stream processor 42, which may be a programmed field programmable logic array is arranged to process the serial bit streams for both the Bluetooth and 802.11 communications. One configuration for receiving signals is shown in
Interface 46 clocks the signals for both the 802.11 and Bluetooth signals to interface 50 in digital processor 18. Both the 802.11 data signals and the Bluetooth data signals are provided in 802.11 frame format and loaded into random access memory 58 in digital processor 18. Digital processor 18 includes a processor 56, such as an ARC or ARM microprocessor and flash memory 20 which contains programs for MAC level digital processing of both 802.11 signals and Bluetooth signals encapsulated in 802.11 frame format, and provides the output message data signals to host interface 52 for transmission to host 60. Likewise signals from the host processor 60 are converted into the frame format of 802.11 standard in digital processor 18 and provided through interface 50 to the communications processing module 16. Digital signals to be transmitted, which are provided to module 16 in 802.11 frame format are stored in FIFO memory 44 and provided to circuit 42. Circuit 42 computes and adds the CRC check data for either 802.11 or Bluetooth format. If the signals are to be transmitted in 802.11 format they are provided to modem 38 which provides a modulated baseband signal to WLAN radio interface 34 for transmission. If the signals are to be transmitted in Bluetooth format circuit 42 removes the 802.11 frame format and provides a data bit stream in Bluetooth format to Bluetooth baseband modem 40 which provides a baseband signal to Bluetooth radio interface 36 for transmission by transmitter 28.
It should be recognized by those skilled in the art that as an alternative to converting Bluetooth message data to 802.11 frame format in circuit 42, 802.11 message data may be converted to and from Bluetooth frame format in circuit 42.
An additional feature that is optionally provided by the configuration of the present invention is that the dual mode mobile unit 10 of the present invention, which controls the associated slave units in its piconet, may signal the slave units at the end of the Bluetooth radio activity (signal 84) to cause the slaves to enter a lower power “STANDBY” mode during the time the dual mode mobile unit undertakes 802.11 communication. The duration of the standby mode may be set by the master signal, may be fixed or may be ended by a renewal of Bluetooth activity by the master.
The configuration of
While there have been described what are believed to be the preferred embodiments of the present invention, those skilled in the art will recognize that other and further changes and modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the true scope of the invention.